mfp: Memory consumption of tables variables

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Источник: http://blogs.msdn.com/b/mfp/archive/...variables.aspx
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I recently made an interesting discovery, that I want to share with you. I was investigating an recursive algorithm that scaled nicely; until it ran out of memory. For each level of the recursion a new class instance was created – this class contained multiple member variables of type Table (as in CustTable). I decided to measure the memory footprint of this construct, and I was much surprised by my findings.

Consider these 3 classes – that each stores the same amount of data, but in different ways:

/// /// Test class containing a table buffer and setting 20 fields /// class Class1 { BOMCalcTrans bomCalcTrans; public void new() { bomCalcTrans.ConsumptionVariable = 50; bomCalcTrans.ConsumptionConstant = 50; bomCalcTrans.CostPriceQty = 50; bomCalcTrans.CostPrice = 50; bomCalcTrans.CostPriceQtySecCur_RU = 50; bomCalcTrans.CostMarkup = 50; bomCalcTrans.NumOfSeries = 50; bomCalcTrans.SalesPriceQty = 50; bomCalcTrans.SalesMarkupQty = 50; bomCalcTrans.CostMarkupQty = 50; bomCalcTrans.CostMarkupQtySecCur_RU = 50; bomCalcTrans.CostPriceSecCur_RU = 50; bomCalcTrans.CostMarkupSecCur_RU = 50; bomCalcTrans.NetWeightQty = 50; bomCalcTrans.CostPriceUnit = 50; bomCalcTrans.SalesPrice = 50; bomCalcTrans.SalesMarkup = 50; bomCalcTrans.SalesPriceUnit = 50; bomCalcTrans.SalesPriceFallBackVersion = 'abc'; bomCalcTrans.CostPriceFallBackVersion = 'def'; } } /// /// Test class containing a hashTable with 20 key/value pairs /// class Class2 { System.Collections.Hashtable hashTable; public void new() { hashTable = new System.Collections.Hashtable(); hashTable.Add(fieldNum(bomCalcTrans,ConsumptionVariable), 50); hashTable.Add(fieldNum(bomCalcTrans,ConsumptionConstant), 50); hashTable.Add(fieldNum(bomCalcTrans,CostPriceQty), 50); hashTable.Add(fieldNum(bomCalcTrans,CostPrice), 50); hashTable.Add(fieldNum(bomCalcTrans,CostPriceQtySecCur_RU), 50); hashTable.Add(fieldNum(bomCalcTrans,CostMarkup), 50); hashTable.Add(fieldNum(bomCalcTrans,NumOfSeries), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesPriceQty), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesMarkupQty), 50); hashTable.Add(fieldNum(bomCalcTrans,CostMarkupQty), 50); hashTable.Add(fieldNum(bomCalcTrans,CostMarkupQtySecCur_RU), 50); hashTable.Add(fieldNum(bomCalcTrans,CostPriceSecCur_RU), 50); hashTable.Add(fieldNum(bomCalcTrans,CostMarkupSecCur_RU), 50); hashTable.Add(fieldNum(bomCalcTrans,NetWeightQty), 50); hashTable.Add(fieldNum(bomCalcTrans,CostPriceUnit), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesPrice), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesMarkup), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesPriceUnit), 50); hashTable.Add(fieldNum(bomCalcTrans,SalesPriceFallBackVersion), 'abc'); hashTable.Add(fieldNum(bomCalcTrans,CostPriceFallBackVersion), 'def'); } } /// /// Test class containing 20 member variables with values /// class Class3 { InventQty bomCalcTransConsumptionVariable; InventQty bomCalcTransConsumptionConstant; CostPrice bomCalcTransCostPriceQty; CostPrice bomCalcTransCostPrice; CostPriceSecCur_RU bomCalcTransCostPriceQtySecCur_RU; CostPrice bomCalcTransCostMarkup; InventQty bomCalcTransNumOfSeries; InventSalesPrice bomCalcTransSalesPriceQty; InventSalesMarkup bomCalcTransSalesMarkupQty; CostMarkup bomCalcTransCostMarkupQty; InventPriceMarkupSecCur_RU bomCalcTransCostMarkupQtySecCur_RU; CostPriceSecCur_RU bomCalcTransCostPriceSecCur_RU; CostPriceSecCur_RU bomCalcTransCostMarkupSecCur_RU; ItemNetWeight bomCalcTransNetWeightQty; PriceUnit bomCalcTransCostPriceUnit; CostingVersionId bomCalcTransCostPriceFallBackVersion; InventSalesPrice bomCalcTransSalesPrice; InventSalesMarkup bomCalcTransSalesMarkup; PriceUnit bomCalcTransSalesPriceUnit; CostingVersionId bomCalcTransSalesPriceFallBackVersion; public void new() { bomCalcTransConsumptionVariable = 50; bomCalcTransConsumptionConstant = 50; bomCalcTransCostPriceQty = 50; bomCalcTransCostPrice = 50; bomCalcTransCostPriceQtySecCur_RU = 50; bomCalcTransCostMarkup = 50; bomCalcTransNumOfSeries = 50; bomCalcTransSalesPriceQty = 50; bomCalcTransSalesMarkupQty = 50; bomCalcTransCostMarkupQty = 50; bomCalcTransCostMarkupQtySecCur_RU = 50; bomCalcTransCostPriceSecCur_RU = 50; bomCalcTransCostMarkupSecCur_RU = 50; bomCalcTransNetWeightQty = 50; bomCalcTransCostPriceUnit = 50; bomCalcTransSalesPrice = 50; bomCalcTransSalesMarkup = 50; bomCalcTransSalesPriceUnit = 50; bomCalcTransSalesPriceFallBackVersion = 'abc'; bomCalcTransCostPriceFallBackVersion = 'def'; } }Now; let us create 1,000,000 instances of each and store them all in a List(Types::Class), and measure the memory footprint of each type of the 3 classes – running as IL and running as pcode.



Notice that using a table as a member variable consumes 6x as much memory as having each field as a member – apparently there is a huge overhead associated with the xRecord+Common functionality.

My conclusion – apparently you cannot have nice code and low memory consumption at the same time. My advice – be careful when using tables as member variables, especially in batch scenarios, i.e. classes derived from RunBaseBatch or used by same.




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Источник: http://blogs.msdn.com/b/mfp/archive/...variables.aspx